One-pot enol silane formation-Mukaiyama aldol reactions: Crossed aldehyde-aldehyde coupling, thioester substrates, and reactions in ester solvents
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) and a trialkylamine base promote both in situ enol silane/silyl ketene acetal formation and Mukaiyama aldol addition reactions between a variety of reaction partners in a single reaction flask. Isolation of the required enol silane or silyl ketene acetal is not necessary. For example, crossed aldol reactions between α-disubstituted aldehydes and non-enolizable aldehydes yield β-hydroxy aldehydes in good yield. In a related reaction, the common laboratory solvent ethyl acetate functions as both an enolate precursor and a green reaction solvent. When thioesters are employed as enolate precursors, high yields for additions to non-enolizable aldehydes are routinely observed.
Downey, C. Wade,Dixon, Grant J.,Ingersoll, Jared A.,Fuller, Claire N.,MacCormac, Kenneth W.,Takashima, Anna,Sediqui, Rohina
supporting information
(2019/10/14)
An asymmetric acetate-Mannich reaction of chiral isatin derived ketimines and its applications
A highly efficient TMSOTf-mediated asymmetric acetate-Mannich reaction of isatin derived tert-butylsulfinyl ketimines and S-phenyl thioacetate was developed to afford the direct synthesis of indole-based β3,3-amino acid thioester with excellent selectivity (dr > 98 : 2). Syntheses of (+)-AG-041R and 3-aminopyrroloindoline have been accomplished utilizing the developed method.
The mukaiyama aldol reactions for congested ketones catalyzed by solid acid of tin(IV) ion-exchanged montmorillonite
Tin(IV) ion-exchanged montmorillonite (Sn-Mont) was found to be an excellent solid acid catalyst for the Mukaiyama aldol reactions of congested ketones with silicon enolates from ketones as well as esters. It was disclosed that Sn-Mont was far more active than other metal ion-or proton-exchanged montmorillonites and typical homogeneous acid catalysts such as TMSOTf and BF3?OEt2.
Takehira, Satoshi,Masui, Yoichi,Onaka, Makoto
supporting information
p. 498 - 500
(2014/04/17)
Addition reaction of imidazoles and thiazoles with silyl enol ethers in the presence of alkyl chloroformate
Silyl enol ethers and ketene silyl acetals reacted with imidazole, thiazole, and their benzo derivatives in the presence of an alkyl chloroformate to give 2-substituted imidazolines and thiazolines in good yields via the intermediacy of unstable N-acylated quaternary salts of azoles. In addition, it was found that silyl enol ethers formed in situ were also useful for the reaction to afford the adducts only by simple sequential addition of five commercially available reagents. (C) 2000 Elsevier Science Ltd.
REACTION OF ACETOXYAZETIDINONES WITH TRIMETHYLSILYLACETYL THIOLESTERS: PREPARATION OF AZETIDINONE-THIOLESTER PRECURSORS TO CARBAPENEMS
Reaction of acetoxyazetidinones, 1 and 2, with trimethylsilylacetyl thiolesters 10 afforded azetidinone-thiolesters, 11 and 12, which are useful intermediates in the carbapenem synthesis.